In a knitting machine, a take-up device is typically employed to wind fabric in rolls. One type of take-up device can wind fabric in rolls having a diameter of about 20 inches. It is not widely employed due to its small capacity. The other type of take-up device, as the widely employed one due to it high capacity, can wind fabric rolls having a diameter of about 46 inches (i.e., fabric weight more than 100 kg). However, for the latter one centrifugal force increases as fabric is winding on a take-up shaft. Further, fabric is pliable in nature. Thus, fabric tends to throw away in the winding process.
U.S. Pat. No. 6,637,241 entitled “Fabric Take-Up Apparatus” aims at solving the above problem. However, the patent still has a drawback as detailed below by referring to FIGS. 1A and 1B. The fabric take-up apparatus 100 comprises two sets of friction mechanisms 110. Each friction mechanism 110 has two operating arms 112 each having axles 112a and 112b both at the same side of and above an axis of the shaft 120 for taking up fabric. A virtual line from one operating arm 112 to the other operating arm 112 is about perpendicular to a virtual line extended upward from the axis of the shaft 120 in the fabric winding process. Initially, force applied on the fabric 10 is provided by weight of the edge of the friction rods 111. Further, the extent of the perpendicularity is almost 90 degrees as fabric 10 continues to wind around the shaft 120 (i.e., diameter of fabric 10 increases). At this time, force applied on the fabric 10 is provided by weight of the whole friction rods 111. Thus, force applied on the fabric 10 is not constant in the fabric winding process. In fact, force applied on the fabric 10 is increasing in the process. For solving this problem, a balancing weight mechanism 130 is provided below the shaft 120. The balancing weight mechanism 130 is adapted to provide same pressing force on the fabric 10 being wound. However, the provision of friction mechanisms 110 and balancing weight mechanism 130 may inevitably increase the manufacturing cost and complicate the components of the fabric take-up apparatus 100. Thus, the need for improvement still exists.